Mathematical model of the ANAMMOX process in multispecies biofilms

This paper presents a mathematical model able to simulate the physical, chemical and biological processes prevailing in a multispecies biofilm including ANAMMOX bacteria under dynamic conditions. A mathematical modeling approach for microbial growth and decay is proposed. The model can simulate the activities of heterotrophs and autotrophs living in a biofilm and evaluate the interactions between the related processes: COD oxidation, denitrification, nitrification and ANAMMOX. The model takes into account all the possible microbial interactions characterizing a multispecies biofilm and is aimed at evaluating the optimal conditions for the development of ANAMMOX bacteria. The model has been applied to simulate the anammox competition in a multispecies biofilm in several conditions. The method of characteristics has been used for the numerical process. The simulations have been performed to evaluate the dynamical response of biofilm in terms of volume fractions of bacteria and concentration trends of substrates. The results show that the model is capable to reveal the microbial stratification in biofilm, evaluating the effect of substrate diffusion on biomass growth.